This invention relates to a low density, dimensionally-stable, extruded propylene polymer foam blown with a blowing agent comprising partly or entirely one or more inorganic blowing agents. The foam offers excellent cushioning properties.
Propylene polymer foams are known in the art, and have been found useful in many applications such as seen in U.S. Pat. Nos. 3,481,455, 3,871,897, 3,932,569, 4,522,955, and 4,832,770. Such foams have been made with a wide variety of organic and inorganic blowing agents.
Given current environmental concerns over the use of organic blowing agents, it would be desirable to have an extruded propylene polymer foam blown partly or solely with inorganic blowing agents. It would be further desirable to have such a dimensionally-stable, low density foam (e.g. 10 to 70 kilograms per cubic meter) for use in cushioning applications. It would also be desirable to have such a foam that is partially open-cell (e.g. at lest 5 percent) since open-cell foams are easier to produce and dimensionally more stable than corresponding closed-cell foams.